Saturday, April 23, 2016

On Perception and Reality

From Quanta:

The Evolutionary Argument Against RealityThe cognitive scientist Donald Hoffman uses evolutionary game theory to
show that our perceptions of an independent reality must be illusions.

As we go about our daily lives, we tend to assume that our
perceptions — sights, sounds, textures, tastes — are an accurate
portrayal of the real world. Sure, when we stop and think about it — or
when we find ourselves fooled by a perceptual illusion — we realize with
a jolt that what we perceive is never the world directly, but rather
our brain’s best guess at what that world is like, a kind of internal
simulation of an external reality. Still, we bank on the fact that our
simulation is a reasonably decent one. If it wasn’t, wouldn’t evolution
have weeded us out by now? The true reality might be forever beyond our
reach, but surely our senses give us at least an inkling of what it’s
really like.

Not so, says Donald D. Hoffman,
a professor of cognitive science at the University of California,
Irvine. Hoffman has spent the past three decades studying perception,
artificial intelligence, evolutionary game theory and the brain, and his
conclusion is a dramatic one: The world presented to us by our
perceptions is nothing like reality.
What’s more, he says, we have evolution itself to thank for this
magnificent illusion, as it maximizes evolutionary fitness by driving
truth to extinction.

Getting at questions about the nature of reality, and disentangling
the observer from the observed, is an endeavor that straddles the
boundaries of neuroscience and fundamental physics. On one side you’ll
find researchers scratching their chins raw trying to understand how a
three-pound lump of gray matter obeying nothing more than the ordinary
laws of physics can give rise to first-person conscious experience. This
is the aptly named “hard problem.”

On the other side are quantum physicists, marveling at the strange
fact that quantum systems don’t seem to be definite objects localized in
space until we come along to observe them. Experiment after experiment
has shown — defying common sense — that if we assume that the particles
that make up ordinary objects have an objective, observer-independent
existence, we get the wrong answers. The central lesson of quantum
physics is clear: There are no public objects sitting out there in some
preexisting space. As the physicist John Wheeler put it, “Useful as it
is under ordinary circumstances to say that the world exists ‘out there’
independent of us, that view can no longer be upheld.”

So while neuroscientists struggle to understand how there can be such
a thing as a first-person reality, quantum physicists have to grapple
with the mystery of how there can be anything but a first-person reality.
In short, all roads lead back to the observer. And that’s where you can
find Hoffman — straddling the boundaries, attempting a mathematical
model of the observer, trying to get at the reality behind the illusion.
Quanta Magazine caught up with him to find out more.

QUANTA MAGAZINE: People often use Darwinian evolution as
an argument that our perceptions accurately reflect reality. They say,
“Obviously we must be latching onto reality in some way because
otherwise we would have been wiped out a long time ago. If I think I’m
seeing a palm tree but it’s really a tiger, I’m in trouble.”

DONALD HOFFMAN: Right. The classic argument is that those of our
ancestors who saw more accurately had a competitive advantage over those
who saw less accurately and thus were more likely to pass on their
genes that coded for those more accurate perceptions, so after thousands
of generations we can be quite confident that we’re the offspring of
those who saw accurately, and so we see accurately. That sounds very
plausible. But I think it is utterly false. It misunderstands the
fundamental fact about evolution, which is that it’s about fitness
functions — mathematical functions that describe how well a given
strategy achieves the goals of survival and reproduction. The
mathematical physicist Chetan Prakash proved a theorem that I devised
that says: According to evolution by natural selection, an organism that
sees reality as it is will never be more fit than an organism of equal
complexity that sees none of reality but is just tuned to fitness.
Never.

You’ve done computer simulations to show this. Can you give an example?

Suppose in reality there’s a resource, like water, and you can
quantify how much of it there is in an objective order — very little
water, medium amount of water, a lot of water. Now suppose your fitness
function is linear, so a little water gives you a little fitness, medium
water gives you medium fitness, and lots of water gives you lots of
fitness — in that case, the organism that sees the truth about the water
in the world can win, but only because the fitness function happens to
align with the true structure in reality.

Generically, in the real
world, that will never be the case. Something much more natural is a
bell curve — say, too little water you die of thirst, but too much
water you drown, and only somewhere in between is good for survival. Now
the fitness function doesn’t match the structure in the real world. And
that’s enough to send truth to extinction. For example, an organism
tuned to fitness might see small and large quantities of some resource
as, say, red, to indicate low fitness, whereas they might see
intermediate quantities as green, to indicate high fitness. Its
perceptions will be tuned to fitness, but not to truth. It won’t see any
distinction between small and large — it only sees red — even though
such a distinction exists in reality.

But how can seeing a false reality be beneficial to an organism’s survival?

There’s a metaphor that’s only been available to us in the past 30 or
40 years, and that’s the desktop interface. Suppose there’s a blue
rectangular icon on the lower right corner of your computer’s desktop —
does that mean that the file itself is blue and rectangular and lives in
the lower right corner of your computer? Of course not. But those are
the only things that can be asserted about anything on the desktop — it
has color, position and shape. Those are the only categories available
to you, and yet none of them are true about the file itself or anything
in the computer. They couldn’t possibly be true.

That’s an interesting
thing. You could not form a true description of the innards of the
computer if your entire view of reality was confined to the desktop. And
yet the desktop is useful. That blue rectangular icon guides my
behavior, and it hides a complex reality that I don’t need to know.
That’s the key idea. Evolution has shaped us with perceptions that allow
us to survive. They guide adaptive behaviors. But part of that involves
hiding from us the stuff we don’t need to know. And that’s pretty much
all of reality, whatever reality might be. If you had to spend all that
time figuring it out, the tiger would eat you.

So everything we see is one big illusion?

We’ve been shaped to have perceptions that keep us alive, so we have
to take them seriously. If I see something that I think of as a snake, I
don’t pick it up. If I see a train, I don’t step in front of it. I’ve
evolved these symbols to keep me alive, so I have to take them
seriously. But it’s a logical flaw to think that if we have to take it
seriously, we also have to take it literally....MORE